The selection of a suitable firing sequence and of a suitable crank star is of fundamental importance in the development of four-cylinder reciprocating piston engines since they decisively determine the mechanical and thermodynamic properties of the engine. The torsional dynamics of the crankshaft, which depend to a substantial extent on the firing sequence must be named in first place here [Wil1935; Nes1958]. In addition, further aspects have to be taken into account such as the gas exchange process, the load on the crankshaft bearing as well as engine operating vibrations. The number of possible firing sequences or possible crank configurations has already been largely described in the relevant literature for reciprocating piston engines having a small number of cylinders with up to six cylinders for reciprocating piston engines in an inline configuration or with up to 12 cylinders in the case of a V configuration, see e.g. [MaaKli1981]. As the number of cylinders increases, the number of possible combinations of firing sequences or crank stars grows disproportionately, however, while the vibration dynamics of the crankshaft and of the total reciprocating piston engine become much more complex at the same time. The selection of a suitable firing sequence for multi-cylinder reciprocating piston engines therefore requires a deep understanding of both the mechanics and the vibration dynamics as well as of the gas exchange process. The systematic evaluation today takes place more and more using computer-assisted simulation and optimizing methods [KnoMal2010, Hen2014a, Hen2014b, BucLau2014, PriOva2014].
There are already a number of patents on firing sequences. U.S. Pat. No. 2,740,389 in this respect deals with the effects of firing sequences on the air path in internal combustion engines having a plurality of cylinders. U.S. Pat. No. 7,979,193 deals with the firing sequences of a V12 reciprocating piston engine in a V 90° configuration. EP 1 793 104 B9 shows a number of advantageous firing sequences for a 15-cylinder reciprocating piston engine in an inline configuration. There is in contrast not yet any knowledge with respect to a V16 engine.
It is therefore the object of the present disclosure to provide a four-stroke reciprocating piston engine in a V configuration having 16 cylinders which has good properties with respect to the above-named factors.
[V1] In a first aspect, the present disclosure deals with optimized firing sequences for a four-stroke reciprocating piston engine in a V configuration having 16 cylinders. Since the optimum firing sequences depend on the direction of rotation of the four-stroke reciprocating piston engine, this first aspect comprises two variations.
In a first variant of the first aspect, the present disclosure comprises a four-stroke reciprocating piston engine in a V configuration having 16 cylinders with a counter-clockwise direction of rotation. The four-stroke reciprocating piston engine has an ignition timing control which ignites cylinders A1 to A8 and B1 to B8 of the four-stroke reciprocating piston engine in one of the following firing sequences, with the direction of rotation and the cylinder numbering being defined by DIN ISO 1204:
a. A1-B2-A5-B4-A7-B8-A3-A8-B5-A6-B7-A2-B3-A4-B1-B6
b. A1-B2-A5-A2-B3-A4-B1-A8-B5-A6-B7-B4-A7-B8-A3-B6
c. A1-B4-A3-B2-A7-B6-A5-B8-B3-A8-B7-A4-B5-A2-B1-A6
d. A1-B4-A3-B2-B5-A2-B1-A6-B3-A8-B7-A4-A7-B6-A5-B8
e. A1-B2-A6-B4-A8-A4-B1-A7-B6-A5-B8-A2-B3-B7-A3-B5
f. A1-B2-A6-B4-A8-B7-A3-A7-B6-A5-B8-A2-B3-A4-B1-B5
g. A1-B2-A6-A2-B3-A4-B1-A7-B6-A5-B8-B4-A8-B7-A3-B5
h. A1-B4-A3-B2-A8-B5-A6-B7-B3-A7-B8-A4-B6-A2-B1-A5
i. A1-B4-B8-A4-B6-A2-B1-A5-B3-A7-A3-B2-A8-B5-A6-B7
j. A1-B4-A3-B2-B6-A2-B1-A5-B3-A7-B8-A4-A8-B5-A6-B7
k. A1-B2-A6-B5-A8-A5-B1-A7-B6-A4-B8-A2-B3-B7-A3-B4
l. A1-B2-A6-B5-A8-B7-A3-A7-B6-A4-B8-A2-B3-A5-B1-B4
m. A1-B2-A6-A2-B3-A5-B1-A7-B6-A4-B8-B5-A8-B7-A3-B4
n. A1-B5-A3-B2-A8-B4-A6-B7-B3-A7-B8-A5-B6-A2-B1-A4
o. A1-B5-B8-A5-B6-A2-B1-A4-B3-A7-A3-B2-A8-B4-A6-B7
p. A1-B5-A3-B2-B6-A2-B1-A4-B3-A7-B8-A5-A8-B4-A6-B7.
Firing sequences a) to j) are advantageous; particular advantages can be achieved by firing sequences a) to d).
In a second variant of the first aspect, the present disclosure comprises a four-stroke reciprocating piston engine in a V configuration having 16 cylinders with a clockwise direction of rotation. The four-stroke reciprocating piston engine has an ignition timing control which ignites cylinders A1 to A8 and B1 to B8 of the four-stroke reciprocating piston engine in one of the following firing sequences, with the direction of rotation and the cylinder numbering being defined by DIN ISO 1204:
a. A1-A6-B1-A2-B5-A4-B7-A8-B3-B8-A5-B6-A7-B2-A3-B4
b. A1-B8-A5-B6-A7-A4-B7-A8-B3-A6-B1-A2-B5-B2-A3-B4
c. A1-B6-B1-A4-B3-A2-B7-A6-B5-A8-A3-B8-A7-B4-A5-B2
d. A1-B6-A3-B8-A7-B4-B7-A6-B5-A8-B1-A4-B3-A2-A5-B2
e. A1-B7-A6-B5-A8-B2-A3-A7-B3-A5-B1-A2-B6-A4-B8-B4
f. A1-A5-B1-A2-B6-A4-B8-A7-B3-B7-A6-B5-A8-B2-A3-B4
g. A1-B7-A6-B5-A8-A4-B8-A7-B3-A5-B1-A2-B6-B2-A3-B4
h. A1-B5-B1-A4-B3-A2-B8-A5-B6-A7-A3-B7-A8-B4-A6-B2
i. A1-B5-A3-B7-B3-A2-B8-A5-B6-A7-B1-A4-A8-B4-A6-B2
j. A1-B5-A3-B7-A8-B4-B8-A5-B6-A7-B1-A4-B3-A2-A6-B2
k. A1-B7-A6-B4-A8-B2-A3-A7-B3-A4-B1-A2-B6-A5-B8-B5
l. A1-A4-B1-A2-B6-A5-B8-A7-B3-B7-A6-B4-A8-B2-A3-B5
m. A1-B7-A6-B4-A8-A5-B8-A7-B3-A4-B1-A2-B6-B2-A3-B5
n. A1-B4-B1-A5-B3-A2-B8-A4-B6-A7-A3-B7-A8-B5-A6-B2
o. A1-B4-A3-B7-B3-A2-B8-A4-B6-A7-B1-A5-A8-B5-A6-B2
p. A1-B4-A3-B7-A8-B5-B8-A4-B6-A7-B1-A5-B3-A2-A6-B2.
Firing sequences a) to j) are advantageous; particular advantages can be achieved by firing sequences a) to d).
The inventors of the present disclosure have in this respect recognized on the basis of a computer-assisted simulation and optimizing method and by a systematic evaluation of the mechanics, vibration dynamics and gas exchange process relevant to the selection of a suitable firing sequence for V16 reciprocating piston engines that the firing sequences claimed in accordance with the present disclosure for four-stroke reciprocating piston engines in a V configuration having 16 cylinders have particularly advantageous properties with respect to torsional vibrations of the crankshaft, the gas exchange process, the load on the crankshaft bearing and the operating vibrations.
The fatigue strength and thus the service life of the engine are increased by the reduced load on the crankshaft and on the crankshaft bearing as well as by the reduction in operating vibrations. The construction effort for the engine and the connection to further components can furthermore be reduced. The small torsion load on the crankshaft due to the optimized firing sequences can furthermore make it possible to make use of inexpensive crankshaft materials. The reduction in the torsional vibrations can furthermore permit the use of a compact torsional vibration damper of a simple design. Both represent a substantial cost advantage in mass production. The engines in accordance with the present disclosure can in this respect be used for the most varied areas of use.
The four-stroke reciprocating piston engines in a V configuration having 16 cylinders in accordance with the present disclosure, both those with an antic-clockwise direction of rotation and a clockwise direction of rotation, optionally have a crankshaft and a flywheel arranged on the crankshaft.
The crankshaft may have cranks at which the connecting rods of the cylinders engage, with the connecting rods of a V segment of the four-stroke reciprocating piston engine each engaging at a common crank. The cranks of the crankshaft in this respect form a so-called crank star.
In a possible embodiment of the present disclosure, the cranks have the following sequence in the direction of rotation, viewed from the flywheel side, with the cranks being numbered in order by C1 to C8 starting from the flywheel side:                i) C1-C8-C3-C4-C7-C2-C5-C6        v) C1-C7-C3-C5-C8-C2-C6-C4.        
A four-stroke reciprocating piston engine in a V configuration having 16 cylinders having one of the two listed crank stars is known as such from the prior art. The use of a firing sequence in accordance with the present disclosure with such a crank star is, however, not known.
The following combinations of crank star and firing sequence may be used in this respect:    Crank star i), one of the firing sequences a, b.    Crank star v), one of the firing sequences k, l, m.
In a second aspect of the present disclosure which can also be used independently of the first aspect, the present disclosure deals generally with the configuration of the crank star of the four-stroke reciprocating piston engine, i.e. with the arrangement of the cranks along the crankshaft.
The present disclosure therefore comprises in a second aspect a four-stroke reciprocating piston engine in a V configuration having 16 cylinders, wherein the direction of rotation can be directed both counter-clockwise and clockwise. The engine has a crankshaft and a flywheel arranged on the crankshaft. The crankshaft has cranks at which the connecting rods of the cylinders engage, with the connecting rods of a V segment of the four-stroke reciprocating piston engine each engaging at a common crank. The cranks of the crankshaft in this respect form a so-called crank star. In accordance with the present disclosure, the cranks have one of the following sequences in the direction of rotation, viewed from the flywheel side, with the cranks being numbered in order by C1 to C8 starting from the flywheel side                ii) C1-C6-C5-C2-C7-C4-C3-C8        iii) C1-C7-C3-C4-C8-C2-C6-C5        iv) C1-C5-C6-C2-C8-C4-C3-C7        vi) C1-C4-C6-C2-C8-C5-C3-C7.        
Four-stroke reciprocating piston engine in a V configuration having 16 cylinders having such crank stars are not known from the prior art. The inventors of the present disclosure have taken into account in this respect that the design of the crank star and in particular the order of the individual cranks along the crankshaft also have a substantial influence on the vibration dynamics of the crankshaft and of the engine. The inventors have in this respect determined, on the basis of a computer-assisted simulation and optimizing method and by a systematic evaluation of the mechanics and vibration dynamics relevant to the selection of a suitable crank star, those crank stars which have particularly good properties with respect to the vibration properties.
The optimized firing sequences in accordance with the first aspect and the optimized crank stars in accordance with the second aspect are in this respect protected independently of one another as subjects of the present disclosure.
A combination of the first and second aspects particularly takes place, however. In this respect, four-stroke reciprocating piston engines are optionally operated with a crank star configured in accordance with the second aspect and with a firing sequence in accordance with the first aspect—
One of the following combinations of crank star and firing sequence is particularly used in this respect:    Crank star i), one of the firing sequences a, b    Crank star ii), one of the firing sequences c, d    Crank star iii), one of the firing sequences e, f, g    Crank star iv), one of the firing sequences h, i, j    Crank star v), one of the firing sequences k, l, m,    Crank star vi) one of the firing sequences n, o, p
The inventors of the present disclosure have recognized in this respect that particularly good results can be achieved by such a coordination of the crank star and firing sequence.
Embodiments of the present disclosure which can be used both with a four-stroke reciprocating piston engine in accordance with the first aspect and with a four-stroke reciprocating piston engine in accordance with the second aspect and with a combination of these aspects will be explained in more detail in the following.
Within the framework of the present disclosure, the V angle of the four-stroke reciprocating piston engine can amount to between 67.5° and 112.5°. The inventors of the present disclosure have recognized in this respect that the V angle also has an influence on the above-named aspects to be optimized. There is furthermore a certain interaction between the firing sequences or crank stars and the V angle.
The V angle in this respect may amount to between 80° and 100°, further optionally between 85° and 95°, further optionally between 87° and 92°, and further optionally between 89° and 91°. The V angle in this respect particularly amounts to 90° C. The inventors of the present disclosure have recognized in this respect that with a V angle of 90°, a particularly favorable arrangement for the vibration dynamics and smooth running of the engine is present. The firing sequences and crank stars in accordance with the present disclosure further produce particularly good results here. Certain deviations of the V angle from this optimum value are possible, however.
The present disclosure is particularly used with firing sequences and crank stars which are configured as equidistant or at least quasi-equidistant. This in turn has advantages for the smooth running, the vibration dynamics and the stresses.
The firing sequences in this respect may have an equidistant or quasi-equidistant firing sequence. In this respect, quasi-equidistant means that the firing sequence is admittedly substantially equidistant, but certain deviations from an equidistant firing interval are permitted. The firing interval between two consecutive ignitions in this respect particularly amounts to between 40° and 50° with an equidistant or quasi-equidistant configuration in accordance with the invention. The firing interval further optionally amounts to between 42° and 48°, further optionally between 44° and 46°. The firing interval between two consecutive ignitions furthermore optionally amounts to 45° in this respect so that an equidistant firing interval is present. The firing interval of 45° in this respect results from the fact that each of the sixteen cylinders fires once as part of two revolutions of the four-stroke reciprocating piston engine.
The crankshaft furthermore may have eight cranks at which the connecting rods of the cylinders engage, with the connecting rods of a V segment of the four-stroke reciprocating piston engine each engaging at a common crank. The cranks in this respect form a crank star. Such a configuration of the crankshaft is of advantage from a technical manufacturing aspect in this respect.
A simple crank star may be used in this respect in which none of the cranks have the same angular position.
The cranks in this respect may be distributed equidistantly or quasi-equidistantly. A quasi-equidistant distribution in this respect means that the distribution is substantially equidistant, but certain deviations from an equidistant distribution are permitted. The angular spacing between cranks following one another at an angle in this respect may amount to between 40° and 50°, further optionally between 42° and 48°, further optionally between 44° and 46°, with the equidistant or quasi-distant distribution in accordance with the present disclosure. The angular spacing particularly amounts to 45° so that equidistance is present. In accordance with the present disclosure, the cranks are thus distributed evenly or substantially evenly over the angular range of 360°.
The four-stroke reciprocating piston engine in accordance with the present disclosure may have a torsional vibration damper which damps the torsional vibrations of the crankshaft. The torsional vibrations are reduced by the embodiment of the four-stroke reciprocating piston engine in accordance with the present disclosure so that the required power loss of the torsional vibration damper can be reduced with respect to known four-stroke reciprocating piston engines. The power loss of the torsional vibration damper in this respect may amount to less than 6‰ of the maximum engine power; further optionally to less than 5‰; further optionally to less than 3.5‰; and further optionally to less than 2.5‰ of the maximum engine power. It is additionally possible due to the required power loss of the torsional vibration damper reduced in accordance with the present disclosure to use favorable and technically less complex vibration dampers.
In accordance with the present disclosure, a viscous oil torsional vibration damper can in particular be used in this respect. This is substantially less expensive in comparison with spring leaf dampers. The use of a spring leaf damper is, however, naturally equally possible in accordance with the present disclosure depending on the application purpose.
The four-stroke reciprocating piston engine in accordance with the present disclosure has a crankshaft and a flywheel arranged on the crankshaft. The power take-off in this respect takes place at the side of the flywheel which is typically connected directly or via a coupling to a shaft which drives a consumer. In this respect, the torsional vibration damper is optionally arranged at the free side of the crankshaft disposed opposite the flywheel. The torsional vibration damper is in this respect particularly arranged outside the engine casing.
The loads reduced in accordance with the present disclosure can make it possible in dependence on the application to produce the crankshaft from a less expensive steel. The crankshaft is in this respect may be produced from a ferritic-pearlitic steel with precipitation hardening from hot-working. Such crankshafts are already known from the automotive sector in which the engines, however, are exposed to substantially smaller loads or have to have a substantially smaller service life. The use of such a less expensive steel instead of the otherwise typical heat-treatable steel likewise becomes possible for the V16 engines in accordance with the present disclosure due to the present disclosure.
Four-stroke reciprocating piston engines in accordance with the present disclosure can be used in a plurality of different configurations and dimensions.
In a possible embodiment of the present disclosure, the displacement per cylinder amounts to between 1 l and 10 l, optionally between 1.5 l and 5 l, further optionally between 2 l and 3 l.
The maximum power of the engine per liter displacement amounts to between 10 kW and 80 kW, further optionally between 20 kW and 60 kW.
The engine can furthermore be operable in a speed range which is between 400 and 3000 r.p.m. The engine can in this respect in particular be operable in a speed range between 600 and 2100 r.p.m. The speed range of a specific four-stroke reciprocating piston engine in accordance with the present disclosure actually used for an application can in this respect make up a part range of this speed range.
The engine may have an engine speed control which operates the engine at a desired engine speed. The engine is optionally controlled in this respect such that the engine again reaches the desired engine speed after brief load changes which allow the actual engine speed to deviate from the desired engine speed. In a possible embodiment, the desired engine speed can be kept constant in this respect. The desired engine speed is in this respect in particular constant over time periods which are long with respect to the typical load changes. In accordance with the present disclosure, the engine control can, however, be designed such that the desired engine speed can be adapted to changing engine conditions and/or load conditions. The desired engine speed can in this respect in particular be tracked slowly for the adaptation.
The engine in accordance with the present disclosure can, however, also be operated using any desired other engine control principles.
The design of the four-stroke reciprocating piston engine in accordance with the present disclosure can be combined with a plurality of different design embodiments of the engine.
The engine in accordance with the present disclosure may have separate intake guides and/or exhaust guides for the two cylinder banks. The engine can furthermore have separate intake and/or exhaust systems for the two cylinder banks.
The engine in accordance with the present disclosure can be a gas engine. In this case, the engine is operable with a gaseous fuel such as hydrogen, natural gas, biogas and/or liquefied gas.
Alternatively or additionally, the engine can also be operable with a liquid fuel. The engine can in this respect, for example, be operable with diesel and/or gasoline.
In a possible embodiment, the engine in accordance with the present disclosure can in this respect only be operable with a gaseous fuel or only with a liquid fuel. Alternatively, however, an operation with both a gaseous fuel and with a liquid fuel is also conceivable.
The engine in accordance with the present disclosure can have direct injection. The engine can furthermore have high-pressure injection. These injections are particularly used with an engine which is operable with liquid fuel.
The engine in accordance with the present disclosure can be operable with a diesel combustion engine or with a gasoline combustion engine.
The engine control can furthermore be configured such that the engine works with a homogeneous-charge, stratified-charge and/or an alternative combustion method. In this respect, one or more combustion methods can also optionally be used in dependence on the engine conditions and/or load conditions.
The engine in accordance with the present disclosure can be a naturally aspirated engine. Alternatively, the engine can have a single-stage or multi-stage supercharging. The engine can in this respect in particular have one or more turbochargers and/or compressors.
A four-stroke reciprocating piston engine in accordance with the present disclosure can be used in a plurality of different applications. Some applications will be described in more detail in the following:
The engine in accordance with the present disclosure can be used as a drive in a heavy-duty machine and/or in mining machinery. A use is furthermore conceivable in an earth-moving machine and/or a transport machine and/or a transfer machine. In a possible application, the engine can in this respect drive a generator or a hydraulic pump via which an undercarriage and/or pieces of working equipment of the heavy duty machine and/or mining machinery and/or earth-moving machine and/or transport machine and/or transfer machine are driven. The engine can alternatively drive an undercarriage and/or pieces of working equipment of the heavy duty machine and/or mining machinery and/or earth-moving machine and/or transport machine and/or transfer machine directly or via a transmission which is optionally connected to the engine by means of a mechanical clutch and/or a torque converter.
The use is in this respect conceivable both for mining machinery for underground mining and for mining machinery for strip mining. The heavy duty machine and/or mining machinery can be both a stationary machine and a mobile machine. If it is a mobile machine, at least the undercarriage is optionally driven by the engine in accordance with the present disclosure.
Possible areas of use of an engine in accordance with the present disclosure are in this respect in particular as a drive for a dump truck or excavator.
A further application of the engine in accordance with the present disclosure is as the main drive for a ship. The crankshaft optionally drives the propeller of the ship in this respect. The shaft of the propeller can in this respect be connected to the flywheel of the engine directly or via a clutch and/or a transmission.
A further area of application of the engine in accordance with the present disclosure is as the main drive in heavy military applications. The engine can in this respect in particular be used in an armored vehicle and/or in a rocket carrier and/or in a speedboat and/or in a submarine.
The engine in accordance with the present disclosure can furthermore be used as a main drive in a rail vehicle. The rail vehicle can in particular be operated diesel electrically in this respect. Alternatively, the drive can take place via a transmission which is further optionally connected to the engine by means of a clutch and/or a torque converter.
The engine in accordance with the present disclosure can furthermore be used as a drive in fluid-conveying technology and/or in the oil and gas industry. For example, the engine can in this respect be used as the drive of a pump and/or of an oil and/or gas extraction machine, of an oil and/or gas transporting machine and/or of an oil and/or gas processing machine.
The engine in accordance with the present disclosure can be used for stationary or mobile power generation.
In a possible application, the load can be connected to the crankshaft in a torsionally rigid manner. Alternatively, the load can, however, also be connected to the crankshaft via a torsionally flexible coupling. Such a torsionally flexible coupling absorbs torsional vibrations to a certain extent in this respect and thus reduces the transmission of still present torsional vibrations of the crankshaft to the driven load.
The present disclosure thus in particular protects the use of a four-stroke reciprocating piston engine in accordance with the present disclosure for one of the above-named applications.
The present disclosure furthermore comprises a machine having a four-stroke reciprocating piston engine in accordance with the present disclosure. The four-stroke reciprocating piston engine is in this respect in particular used to drive the machine or a piece of working equipment of the machine. The machine in accordance with the present disclosure can in this respect both be a stationary machine and a mobile machine.
The machine in accordance with the present disclosure is in particular one of the above-named applications. The machine in accordance with the present disclosure can, for example be a heavy duty machine and/or mining machinery and/or an earth-moving machine and/or a transport machine and/or a transfer machine, a ship a rail vehicle, a heavy military machine, a fluid-conveying machine, an oil and/or gas extraction machine, an oil and/or gas transport machine and/or an oil and/or gas processing machine and/or a power generation unit. The machine can in this respect in particular be configured such as was presented in more detail above with respect to the applications in accordance with the present disclosure. The engine in accordance with the present disclosure can be configured such as was presented in more detail above.
The present disclosure furthermore comprises an ignition timing control or software for an ignition timing control for a four-stroke reciprocating piston engine having 16 cylinders. The ignition timing control or the software in this respect implement at least one of the firing sequences indicated above with respect to the first aspect. The ignition timing control can in this respect be an ignition timing control predefined by the construction design of the engine, for example an ignition timing control driven mechanically via a camshaft. Alternatively, however, it can also be an electronically controlled ignition timing control. The ignition timing control or the software in this respect optionally implements an operation of the four-stroke reciprocating piston engine such as was presented in more detail above and/or can be used in a four-stroke reciprocating piston engine which is configured and/or operated such as was presented in more detail above.
The ignition timing control may be an ignition timing controller. The controller may comprise a microprocessor and a memory, the microcontroller executing a program installed in the memory. The controller and/or microprocessor may be adapted to electronically control components of the engine in such a way as to implement one or more of the firing sequences of the present invention. In particular, the controller and/or microprocessor may control electronically controlled fuel injectors and/or valves of the engine in response to sensors such as a crankshaft position sensor.
The present disclosure furthermore comprises a method of operating a four-stroke reciprocating piston engine in a V configuration having 16 cylinders, wherein the cylinders are operated with one of the firing sequences indicated in more detail above with respect to the first aspect. The four-stroke reciprocating piston engine is in this respect optionally configured and/or is operated such as was presented in more detail above.
The present disclosure will now be presented in more detail with reference to embodiments and to drawings.